ilya77, hello!
How did your adventure end?
I also have KV6103-PE1(A) and U-Boot crashed.
U-Boot 2010.06-svn167559 (Sep 03 2019 - 14:54:44)
spi_w25q256fv_solve_flash_lock_qe_enable(268): Error: Disable Quad failed! reg:0 x2
spi_w25q256fv_entry_4addr enable is 1
*** Warning - bad CRC, using...